1. Field of the Invention
This invention relates generally to faucets and other water delivery devices, and more particularly to faucets and other water delivery devices in which a material is cast around a protective liner in order to form a water delivery device that meets current safety standards including, but not limited to the National Sanitation Foundation International (NSF) and the Canadian Standards Association (CSA).
2. Description of the Prior Art
In order to meet NSF an CSA or other state, national or international safety standards for water delivery devices, many faucets and other water delivery devices presently in the art are formed primarily from low-lead brass alloys and then plated with either chrome, brass, PDM or nickel type plating to achieve their desired finish. Other water delivery devices utilizes plastic coverings with snap-on liners with the covering provided to conceal the liner. Such liners are typically lined with copper tubing or molded plastic tubes. The liners and coverings of such plastic faucets are separately formed and assembled after individual formation of the various components. For example, the covering may include a top decorative portion for housing the liner. A separate bottom portion is then attached to the decorative portion, as by snapping or fastening, to enclose the liner within the device.
In many applications it would be desirable for water delivery devices to be formed from a stainless steel core or liner with other materials such as bronze, brass, ceramics, or plastics providing an exterior decorative shell. Stainless steel has been identified by most current safety standards as the preferred material for drinking water delivery devices. Unlike other materials commonly used in water delivery devices, stainless steel does not leach lead, arsenic or other potentially harmful or damaging particles into the water as the water flows through a stainless steel tube. Stainless steel, however, is very difficult to work with and form into desired shapes for decorative purposes and is more expensive than traditional faucet making materials. As such, the commercial use of stainless steel in decorative water delivery devices has been non-existent.
While stainless steel is the preferred material, it would also be desirable to be able to cast copper tubing or other lining materials directly into decorative, functional or other coverings formed from copper, bronze, pewter, ceramics, plastics or other materials. For example, it would be advantageous in the art to form a bronze water delivery with a stainless steel liner that prevents leaching of the bronze materials into the water. Thus, it would be advantageous to allow the flexibility of design by using moldable or castable materials to form the decorative portions of the water delivery device while lining the inside of the water delivery device to prevent leaching.
One such plumbing part that has been disclosed in the prior art is shown in U.S. Pat. No. 5,579,823 (the xe2x80x9c""823 patentxe2x80x9d) to Erwin F. Mikol and Andrew G. Pawlyszyn, now assigned to Moen Incorporated of North Olmsted, Ohio. The ""823 patent discloses a plumbing part made from a permanent core and a body cast around the core. The core is formed of a material which meets the requirements as to the permitted leachability of lead and/or other undesirable materials from the core into water flowing through it. The core material has a melting point preferably at least 200 degrees F. above that of the cast body. The core also has a coefficient of expansion which is equal to or least than that of the material forming the cast body.
The core of the ""823 patent is formed of #304 stainless steel and includes an upper stamping and a lower stamping. These two elements have outwardly extending flanges that are joining by welding, crimping or folding to thus join the upper and lower waterways in to a single unitary core. Thus, the core is formed from at least two separate parts that must be joined together to form the waterways of the desired core.
Thus, it would be advantageous to provide a plumbing part forming a water delivery device that utilizes a core that eliminates the concern of leaching of lead or other undesirable material from the water delivery device to the water, the core being formed from a length of tubing.
It would be a further advantage to provide a plumbing part forming a water delivery device which is relatively easy to manufacture and does not require any significant separate manufacture of the core prior to formation of the plumbing part.
It would be yet a further advantage of the present invention to provide a casting process which prevents inadvertent melting of the core during the formation process.
It would be still another advantage to provide a casting process which allows for use of materials with different coefficients of expansion without adversely effecting the finished plumbing part.
Accordingly, a plumbing part in the form of a water delivery device, in accordance with the principles of the present invention, is comprised of a protective liner through which potable water can flow. The protective liner is encased in a casting of a desired material, such as bronze or brass. Fittings required to attach the water delivery device to sinks, bathtubs or other water sources and to allow for insertion of various aerators and other flow devices are also encased in the casting. The various fittings are pre-assembled to the liner prior to casting to ensure a water-tight seal between the liner and the fittings prior to casting.
One method of forming a plumbing part in the form of a water delivery device in accordance with the present invention comprises providing a pattern of the desired exterior shape of the water delivery device. The pattern may be formed from an easily moldable material such as wood or plastic or some other formable material. The pattern is formed by forming a complete full-scale model of the desired exterior shape of the plumbing part. The model is then cut or otherwise divided in half along a longitudinal axis of the model. The pattern is formed by placing and attaching each half of the model inside a box-like structure. The pattern is then filled with casting sand. The sand is packed firmly around the pattern. Once the pattern is packed tightly with sand, the pattern and the casting sand are separated leaving a sand mold of one half of the water delivery device. The other half of the mold for the water delivery device is essentially a mirror image of the first and is formed by packing casting sand around the pattern for the second half in the same manner. Of course, those of skill in the art will appreciate that other methods of casting and casting materials may also be employed in accordance with the principles of the present invention. When combined, the two mold halves form a mold cavity in the shape of the entire model of the water delivery of the present invention.
The protective liner is formed into a shape that will position the liner generally along a central portion of the mold cavity of the mold. In one embodiment, the liner consists of a stainless steel tube, but it can also be made from other materials known in the art. The tube is thus bent into a particular shape matching the general curvature of the longitudinal length of the water deliver device so as to reside generally long a center-line of the water delivery device.
Because heat generated during casting may have an adverse effect on the liner, especially in areas where the casting material is to be relatively thick, a sand-like or other type of core material is applied to the exterior of the liner along its length where the casting material may pose a threat to the integrity of the liner. This is generally at the wider or more voluminous regions of the mold cavity. Thus, in order to maintain a relatively consistent casting thickness about the liner, the liner is packed or otherwise covered along certain portions thereof with a liner protection material (e.g., sand core). As such, a relatively regular annular space can be formed around the liner protection material along a complete length of the liner. It is noted that the liner protection material not only protects the liner from becoming damaged due to excessive heat during the casting process, but also reduces the amount of casting material needed to form the finished water delivery device in accordance with the principles of the present invention.
The annular space between the mold cavity and the liner protection material creates a space where the molten metal flows to form the exterior of the water delivery device and also defines the appropriate thickness of the casting portion of the water delivery device. The liner protection material helps to dissipate heat from the casting and prevents the heat from damaging the liner or otherwise allowing the casting material to melt holes in the liner. As previously discussed, the liner protection material also reduces the weight of the final casting and reduces the amount of casting material needed to complete the cast. It should be noted that, in some locations of the mold, the thickness of the casting material is thin enough that the liner itself can provide sufficient cooling during the casting process to prevent the casting material from melting or otherwise compromising the integrity of the liner. In such regions, the core material may not be necessary.
Such a core material, however, produces gas when exposed to the molten casting material. In order to help prevent such gases from escaping through the casting material resulting in holes blown through the side of the casting, a core vent is provided which is in fluid communication with the core material and the exterior of the mold. Such a core vent may be formed from such materials as braided metal, heat resistant fabrics, wax, perforated metal tubing, or other materials that can be placed in the mold and in fluid communication with the liner protection material to allow gases formed within the casting as a result of the heat of the casting material to flow into the core vent at points along its length and flow out of the mold to relieve gas pressure within the casting. In one embodiment, the core vent is formed from a braided cloth tube that is placed in the sand core. As gasses are generated by the core material, they naturally pass through the braided tube wall and into the interior of the core vent. By placing the interior passage of the core vent in communication with the outside of the mold, the gasses can flow out of the mold through a desired location in the casting rather than through the side of the casting producing an undesirable blow hole. In another embodiment, the core vent may be attached to a small piece of copper tubing that acts as a chimney.
The liner is placed in the casting mold in the mold cavity formed by the pattern of the water delivery device as previously discussed. The liner extends beyond both ends of the mold cavity in order to support the liner within the mold cavity. As desired for the type of water delivery device being formed, various fittings may be attached to the liner and thus placed in the mold. Such fittings may allow the finished water delivery device to be attached to a water source or other plumbing fixtures.
A flange is attached as by welding, soldering or other means of joining known in the art to a point proximate to the discharge opening of the liner.
In the situation where the fitting for attaching the inlet of the water delivery device is cast into the component, fixing both ends of the liner during a molten metal casting process may cause cracks in the casting as a result of the contraction of the casting during the cooling stages. That is, because the casting and liner will have different coefficients of thermal expansion due to their differences in material compositions and because the liner is significantly cooler than the molten casting material, the liner should be allowed to move relative to the casting metal as the casting metal contracts to prevent tears or damage to the casting material that may otherwise occur as a result of the shrinking of the casting material relative to the liner during the cooling process.
As such, a sleeve is attached to the inlet fitting as by welding or other means of attachment known in the art. The sleeve has an interior diameter that allows the liner to fit therein. After casting, as the casting cools and shrinks relative to the liner, the liner will protrude from the sleeve. The proximal or inlet end of the liner protruding from the exposed end of the sleeve can be cut and attached to the sleeve by welding, soldering or other means of joining known in the art which provides a water-tight seal between the sleeve and the liner.
Once all of the desired components are placed in the first half of the mold, the second half of the mold is fitted to the first half to effectively close the mold. Molten material is poured into the mold cavity to encase the stainless steel liner. Once the casting material has solidified, the mold is opened and the casting of the water delivery device is removed. The small molten metal resistant tube used to vent gases from the mold is twisted until loosened and then removed. Because the liner protection material turns into a particulate form after being exposed to the heat from the casting process, the core material can generally be shaken out through the hole left by the molten metal resistant tube. The excess liner at the outlet end of the water delivery device is cut off and a fitting is attached to the inlet of the liner. The outlet of the water delivery device is counterbored until the flange is reached. The opening created by the drill is then threaded as by tapping in order to allow an aerator to be attached.
Finally, the flashing formed between the mold halves is removed as by grinding or sanding and the exterior of the water delivery device is polished to the desired finish.